1. Field Of The Invention
This invention relates to a liquid fuel injection pumping apparatus for supplying fuel to internal combustion engines and of the kind comprising a body part, a bore, and a plunger reciprocable in the bore, a cam ring in the body part and having a cam lobe for imparting inward movement to the plunger to discharge fuel to an outlet, a low pressure pump for supplying fuel to said bore during the filling stroke of the apparatus, and valve means for controlling the outlet pressure of the pump so that it varies in accordance with the speed at which the apparatus is driven, a fluid pressure operable device responsive to the outlet pressure of the pump for controlling the angular setting of said cam ring, an angularly adjustable throttle member mounted in a drilling in the body part, a groove on the throttle member and a port opening into the drilling, said port and drilling constituting part of the flow path for fuel between the outlet of the pump and said bore and the degree of registration of the groove and the port being varied by altering the angular setting of the throttle member thereby to vary the quantity of fuel supplied to the bore.
2. Description Of The Prior Art
An example of such an apparatus is described in the specification of British Pat. No. 1171791 in which the throttle member is connected to a mechanical governor so as to be movable angularly thereby to control the quantity of fuel which is supplied to the bore. The throttle member is provided with an axial groove which communicates with the outlet of the pump. In order to provide an independent control of the maximum flow of fuel the throttle member is axially movable in the bore and for this purpose it is subjected to the outlet pressure of said pump. Moreover, the throttle member carries an arm which defines an inclined stop surface for engagement by a stop member and the arrangement is such that as the member is moved axially by an increasing outlet pressure, the throttle member will be forced to move angularly thereby altering the quantity of fuel supplied to the bore. The throttle member is biased by a spring against the force exerted by the outlet pressure of the pump and since the outlet pressure varies with speed so the maximum fuel delivery will vary with speed.